Chemometric discrimination of eight citrus plants utilizing chromatographic and spectroscopic techniques and insights into their biological potentials

Citrus sinensis balady orange, C. sinensis navel orange, C. paradisi, C. limon, C. sinensis bloody orange, C. sinensis sweet orange, C. aurantium var. amara and C. reticulata were successfully discriminated using chromatographic and spectroscopic techniques coupled with chemometrics. Ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) managed to discriminate the alcohol extract samples to six and five clusters respectively on exposing the obtained data to Principle component analysis (PCA). High performance liquid chromatography (HPLC) was utilized for differentiating the different samples based upon their rutin content where C. aurantium demonstrated the highest rutin content (0.795 mg/mL). LC-ESI-MS led to the identification of 35 compounds belonging mainly to flavonoids and limonoids. In vitro biological investigations including DDPH, ABTS, FRAP and enzyme inhibitory activities revealed the promising antioxidant, neuroprotective, anti-hyperglycaemic and skin-lightning potentials of citrus samples that were correlated with the total phenol and flavonoid contents. In silico ADME/TOPKAT reflected the acceptable pharmacokinetic, pharmacodynamic and toxicity properties of the identified secondary metabolites.